US Patent 7207573 Chuck assembly

To provide an excellent chuck assembly that is superior in assembling workability, may be produced in low cost and is superior in mass-production property, in which a rotary sleeve (2) provided on a body (1) is rotated, jaws (4) engaged with rotary nuts (3) are moved back and forth to be opened and closed by the rotation of the rotary nut (3) rotated together with the rotary sleeve (2) and a tool is clamped by the jaws (4), a ring member (8) is provided in the rotary nuts (3), a convex and concave engaging means is provided between the ring member (8) and the rotary sleeve (2), and the ring member (8 and the rotary sleeve 2 are retained and prevented from falling apart from each other by the convex and concave engaging means.